Activated carbon spheres with hierarchical porous structures were synthesized. The obtained carbon spheres exhibit a uniform, monodispersed, and mesoporous structure with narrow pore size distribution of micropores, mesopores, and macropores. The proposed method for synthesis is simple. Electrochemical analyses show that the activated carbon spheres yield a high-rate operation, a specific capacitance of 217F g(-1) at a low current density of 0.2 A g(-1), and a relatively high specific capacitance of 90 F g(-1) at a high current density of 50 A g(-1). The carbon spheres also show high reversibility and excellent electrochemical stability.